Here's two more options, hypothetically speaking:

(1) Use another airline that participates in Amex Membership Rewards. You can puchase 500,000 points annually at 1/4 cent per mile on a US Amex card.

(2) Buy miles through an "employee-incentive" program, if BA has one. AA definitely does. Enroll your company, or get a friend with a small business to enroll. Usually the max on airlines with these programs is 25,000-50,000 per FF account per year, but if your 250K miles needed is really 2x125K then you can put miles in a second account to use for the other person's ticket. Usually costs about 1/4 cent per mile, plus a service charge under $100. If you're really smooth, there might still be time to have miles retroactively post to 2002, so that you can max out the 2002 and 2003 annual limits.